Motor compressor particularly for small refrigerating machines

ABSTRACT

The invention relates to a motor compressor assembly of the type used for small refrigerating machines. It involves a construction for forming noise-reducing chambers wherein the chambers are formed between recesses in a central bore of the casing and a cup shaped element inserted in the central bore. Grooves are formed in the central bore which are covered by the peripheral wall of the insert and the grooves form passages connecting the noise reducing chambers.

United States Patent Bendt Wegge Romer Ulkebol;

Vegan Vllbjorn, Nordborg; Bent M. K. l'loltae, Skovby, all of. Denmark (72] Inventors [2] I Appl No. 847,637

[22] Filed Aug. 5. I969 [45] Patented July 13. I97] [73] Alsignee Dlnltls A/S Nordborg. Denmark [541 MOTOR COMPRESSOR PARTICULARLY FOR SMALL REFRIGERATING MACHINES 9 Claims. 3 Drawing Figs.

{52] U5. Cl 91/161 [5!] Int. F0lb29/00 [50] Field of Search 0. 230/232.

[56] Reierences Cited UNITED STATES PATENTS 2.823.850 2/1958 Hintze. r r. 230/58 3 4 l .608 7/1964 Enemark 230/232 Primary Examiner- Robert M Walker Attorney-Wayne B Easton ABSTRACT: The invention relates to a motor compressor assembly of the type used for small refrigerating machines. It involves a construction for forming noise-reducing chambers wherein the chambers are formed between recesses in a central bore of the casing and a cup shaped element inserted in the central bore. Grooves are formed in the central bore which are covered by the peripheral wall of the insert and the grooves form passages connecting the noise reducing chambers.

PATENTEU JUL 1 3 15m SHEET 1 OF 2 Fig 2 MOTOR COMPRESSOR PARTICULARLY FOR SMALL REFRIGERATING MACHINES The invention relates to a new and improved motor compressor. U.S. Pat. application Ser. No. 743,726 filed July 10, 1968 in the name of Knud Vagn Valbjorn, Heinz Mahncke and Steinar Skog is for a motor compressor, particularly for small refrigerating machines, and having a shaft held in a main bearing and a supporting bearing, the main bearing being formed on a motor-carrier element, integral with the cylinder and noise-reducing chambers. and the supporting bearing being formed on an insert connected to the motoncarrier element, characterized in that the insert is of cup shape, extends axially at least over part of the crank, has an orifice in the zone of the cylinder and is held at its outer periphery in the carrier element. Furthermore, the noisereducing chambers disposed in the carrier element can be open towards the crank and are only closed by the cup-shaped insert.

in this construction, the insert is secured firmly exclusively at its periphery, particularly by its being pressed in, the supporting bearing being well centered and precisely aligned in the axial direction. The insert can be easily manufactured and machined. Since the insert closes the noise-reducing chum bers, these can be produced in the motor-carrier element with large openings so that the core necessary in the casting can be easily extracted.

For the purpose of interconnecting the noise-reducing chambers, it has been proposed to provide the insert with an opening in the region of each of the noise-reducing chambers and to connect the openings with the help of arcuate passage parts filled to the inside of the insert. Another suggestion was that of forming grooves in the motor-carrier element in the end face presented to the open end ofthe cup, for the purpose of connecting the noise-reducing chambers, and of covering these grooves with a ring which can be held by the cup-shaped inserts. The connection of the noise-reducing chambers to the suction chamber was by way of pressed-in tubular portionsv The present further embodiment of the subject-matter of the said U.S. Pat. application Ser. No. 743,726 has for its aim the provision of further improvements relating to the connec tions of the noise-reducing means.

According to the present invention, there are provided in the inner peripheral surface of the cavity in the motorcarrier element, grooves which are covered by the peripheral wall of the insert and form passages connected to the noisereducing chambers.

The grooves can be provided during the machining of the inner periphery of the motor-carrier element, which machining is necessary in any case. The passages are formed merely by covering with the insert. Furthermore, there is sufficient space available on the peripheral surface to provide passages of a length sufficient for a throttling action. In some circumstances, the surface, rendered more irregular by the grooves, improves the hold ofthe pressed-in insert.

Expediently, the passages in each extend in planes at right angles to the axis of the motor. This facilitates the machining.

Advantadeously, the passages are in two planes. the first of which extends close to one edge of the insert and the second close to the other. in this way, the noise'reducing chambers can be produced with the greatest possible opening, so that a casting core can be easily extracted. Furthermore, the insert is held near each of its two end faces by two peripheral portions separated by the groove.

In the case of a motor compressor having a vertically disposed shaft and a cylinder located at the top, it is advantageous to connect the groove in the upper passage plane to a suction orifice on the underside of the carrier element, by way ofa bore in a wall bounding a noise-reducing chamber. in this arrangement, the bore is of considerable length; any required throttle resistance can therefore be imparted to it. Furthermore, the suction orifice is located at a point protected from oil-spray. The latter applies in particular if the carrier element has an outwardly extending projection, e.g. for fitting a backing spring, and the suction mouth is located near the projection.

Further simplifications can be achieved if two series arrangements each comprising two suction noise-reducing chambers are disposed in parallel and the groove in one passage plane connects the two first noise-reducing chambers of both series arrangements, a common supply passage in between opening into this groove. Thus, a single groove suffices in one of the passage planes.

in a preferred embodiment, the effective portions of the grooves in both planes extend over the entire length of at least one noise-reducing chamber in the peripheral direction and these sections are connected to the noise-reducing chambers at diagonally opposite points. in this way the longest possible effective sections are obtained in the two passages and the required throttling resistance can be accordingly imparted to them. Furthermore, the gas in the noise-reducing chambers has to travel the greatest possible path, so that an optimum period of dwell is obtained.

Additionally, it is possible to provide a single groove in the second passage plane, which connects each of the outlets of two noise-reducing chambers to a series-arranged noisereducing chamber and also interconnects these outlets. In this way, the connecting passages of two series arrangements can be produced in one operation. A connection between the two series arrangements causes no trouble since virtually the same pressure obtains at the point of connection.

In a further arrangement, it is of advantage for the lower side of the groove in the lower passage plane to be disposed at the same level of the lower side of the noise-reducing chambers, or lower, and for a cross-bore of smaller cross section than this groove to lead into the suction chamber possibly by way of the suction bore, open at the bottom. Oil which may have penetrated into the noise-reducing chambers during transport, for example, can flow away by way of this crossbore.

The invention will now be described in more detail by reference to an embodiment illustrated in the drawing, wherein:

FIG. 1 is a longitudinal section through the upper part of a motor compressor in accordance with the invention,

HO. 2 is a section on the line A-A of FIG. i, and

FIG. 3 is a developed view of the inner peripheral surface of the cylindrical cavity in the carrier element.

The motor compressor comprises a carrier element 1, in which are accommodated a cylinder 2 for a piston 3, a main bearing 4 for a motor shaft 5, and noise-reducing chambers 68. Pressed into a cylindrical cavity 10 in the carrier ele ment 1, is an insert II which has a cylindrical wall 12 and a base [3 with a supporting bearing 14 for the motor shaft 5. The piston is axially reciprocable by means of a connecting rod [5 and a crank bearing 16 of a crank 17 of the shaft 5. Secured by means of a screw bolt l8 to the upper end of the shaft 5 is a disc [9 which acts as an axial bearing and which has, on that side remote from the crank 17, an extension 20 with an additional weight 21, said extension and weight acting as a compensating weight.

The cylinder chamber is closed by a cylinder head 22; the stator and rotor of the motor are not illustrated in further detail.

The noise reducing chambers are separated from each other by substantially radially extending transverse walls 23, 24 and 25. In the transverse wall 23 runs a bore 26, which leads from a suction orifice 27 on the underside of the carrier element 1 to a first groove 28 in the inner periphery of the cavity 10. This groove 28 is located close to the upper end of the insert l]. A second similar groove 29 is located near the lower end of the insert II. A cross-passage 30 extends in the transverse wall 23 from the last-mentioned groove to the bore 26. The suction mouth 27 is located near a projection 31 on which the carrier element 1 is supported on the case by way of springs, not illustrated.

As the developed view of the periphery of the cavity 10, seen in FIG. 3, shows, there pass through this cavity a bore 32 for movement of the piston 3. and four orifices 33-36 as sociated with the noise-reducing chambers 69, The orifice 33 has an upwardly extending projection 37 and the orifice an upwardly extending projection 38 where the peripheral groove 28 communicates with the noise-reducing chambers ti and 8, The adjacent sections 39 of the groove 28 are ineffective as regards the conveyance of gas and merely serve to break up the peripheral surface to enable the insert II to be pressed in more easily. At the diagonally opposite points, the openings 33 and 35 have projections 40 and 41 where the noise-reducing means 6 and 8 communicate with the lower groove 29, The orifices 34 and 36 extend so far down that the intersect the groove 29, The outlets 42 and 43 from the noisereducing chambers 7 and 9 are located near the cylinder head 27. The groove 29 not only establishes connection between the chambers 6 and 7, and 8 and 9 respectively, but also has a section 44 which is ineffectual as regards the conveyance 01 gas and which on the one hand enables the groove 29 to be produced in a continuous manner and on the other carries oil flowing from the noise reducing chambers 6-9 to the cross bore 30, whence the oil can be diverted into the suction chamber by way of the bore 26. When the grooves 28 and 29 are closed by the insert I l, the course of flow of the suckedup gas is as follows The gas flowing through the bore 28 is distributed in roughly equal parts to the noise-reducing chambers 6 and 8 by way of the sections of the groove 28 provided on both sides. From the chamber 6, the gas flows over the lefthand section of the groove 29 into the chamber 7 and thence by way of the outlet 42 into the suction valve chamber. The gas flows through the right-hand section ofthe groove 29 from the chamber 8 to the chamber 9 and, by way of the outlet 43 of the latter, likewise to the suction valve chamber,

The noise-reducing chambers can extend over roughly the entire height ofthe cavity, i.e. behind the wall portions accommodating the grooves 28 and 2.9V in each case, the core required in casting can be easily removed through the large openings 33-36, and the inside wall of the chambers 68 can be readily cleared of residual particles ofthe core.

We claim:

1. A compressor assembiy comprising a casing section having a cylindrical bore, a ring-shaped insert disposed in said bore, a plurality of noisereducing chambers formed by recesses in said bore and said insert, registering openings in said bore and said insert forming a crank opening, and a cireumlerentially extending header passage formed jointly by a recess in said bore and said insert, said header passage joining at least two of said chambers to form fluid communication therebetween.

2. A compressor assembly according to claim 1 including at least two of said header passages, each of said header passages being in a plane normal to the axis ofsaid bore,

3. A compressor assembly according to claim 2 wherein said header passages are adjacent opposite axial ends of said insert.

4. A compressor assembly according to claim 3 including a separating wall between two of said chambers, air inlet means in said casing section, a feed passage in said wall having fluid communication with one of said header passages and said air inlet means.

5. A compressor assembly according to claim 4 wherein said casing section has a projecting portion, said air inlet means being at least partially formed in and by said projecting por tion,

6. A compressor assembly according to claim 2 including at least two pairs of said chambers with one of said header passages connecting the chambers of one of said pairs and the other of said header passages connecting the chambers of the other of said pairs, and a common supply passage for said header passages,

7. A compressor assembly according to claim 2 wherein one ofsaid chambers forms a generally rectangularly shaped opening in said bore, one ofsaid header passages having fluid communication with only the corner ofsaid one of 5m chambers,

and the other of said header passages having fluid communication with only the diagonally opposite corner of said one of said chambers,

8, A compressor assembly according to claim 2 including at least two pairs of said chambers with one of said header passages being connected to the chambers of one of said pairs and the other of said header passages being connected to all of the chambers ofsaid two pairs.

9. A compressor assembly according to claim 3 wherein said casing section has air inlet means and the lower one of said header passages is in the vicinity of the lower portions of said chambers, and a conduit passage opening into said lower header passage and having fluid communication with said air inlet means. 

1. A compressor assembly comprising a casing section having a cylindrical bore, a ring-shaped insert disposed in said bore, a plurality of noise-reducing chambers formed by recesses in said bore and said insert, registering openings in said bore and said insert forming a crank opening, and a circumferentially extending header passage formed jointly by a recess in said bore and said insert, said header passage joining at least two of said chambers to form fluid communicAtion therebetween.
 2. A compressor assembly according to claim 1 including at least two of said header passages, each of said header passages being in a plane normal to the axis of said bore.
 3. A compressor assembly according to claim 2 wherein said header passages are adjacent opposite axial ends of said insert.
 4. A compressor assembly according to claim 3 including a separating wall between two of said chambers, air inlet means in said casing section, a feed passage in said wall having fluid communication with one of said header passages and said air inlet means.
 5. A compressor assembly according to claim 4 wherein said casing section has a projecting portion, said air inlet means being at least partially formed in and by said projecting portion.
 6. A compressor assembly according to claim 2 including at least two pairs of said chambers with one of said header passages connecting the chambers of one of said pairs and the other of said header passages connecting the chambers of the other of said pairs, and a common supply passage for said header passages.
 7. A compressor assembly according to claim 2 wherein one of said chambers forms a generally rectangularly shaped opening in said bore, one of said header passages having fluid communication with only the corner of said one of said chambers, and the other of said header passages having fluid communication with only the diagonally opposite corner of said one of said chambers.
 8. A compressor assembly according to claim 2 including at least two pairs of said chambers with one of said header passages being connected to the chambers of one of said pairs and the other of said header passages being connected to all of the chambers of said two pairs.
 9. A compressor assembly according to claim 3 wherein said casing section has air inlet means and the lower one of said header passages is in the vicinity of the lower portions of said chambers, and a conduit passage opening into said lower header passage and having fluid communication with said air inlet means. 